FURIN and COVID-19: Considering the important role played by some of the crucial receptors and targets in COVID-19 (Hoffmann et al., 2020), we determined the protein expression of SARS-CoV-2 receptor angiotensin converting enzyme 2 (ACE2) and aiding proteases like transmembrane protease serine protease-2 (TMPRSS-2) and spike protein convertase furin in lung homogenates of non-smokers, smokers, COPD, and IPF subjects.